1. Technical Field
The present disclosure relates to a lighting control system for controlling lighting on and off and light intensity of a vehicle lamp including a plurality of lamps.
2. Related Art
In general, in addition to a main lamp such as a head lamp (HL), an auxiliary lamp such as a clearance lamp (CLL) or a daytime running lamp (DRL) is provided in an automobile. In recent years, in automobiles, as a lighting control device for the plurality of lamps, a lighting control system which performs a lighting control using a body electronic control unit (ECU) for performing various controls of the automobiles has been suggested. For example, FIG. 6 is a conceptual configuration view of a lighting control system of the HL including the CLL and the DRL, and here, only lamps mounted on one side of the automobile, that is, the left side thereof are shown. In an HL 100, a high beam lamp (HiL) performing illumination by a main beam and a low beam lamp (LoL) performing illumination by a low beam are mounted in one lamp housing, and a DRL/CLL 101 in which the CLL and the DRL are integrally mounted in a separate lamp housing is provided. The HiL has a bulb BUL as the light source, and the LoL has an LED1 (light-emitting diode), which is light-emitted by an LED drive circuit 102, as the light source. Moreover, the CLL and the DRL have one LED2 (light-emitting diode) as a common light source, and the lighting of the CLL or the DRL is controlled as the lamp by switching light intensity at the time of light-emitting of the LED2 by the LED drive circuit 102 used for the low beam lamp LoL.
The lighting controls of the HL 100 and the DRL/CLL 101 are performed by the body ECU (B-ECU) 103. The body ECU 103 generates lighting control signals based on a switching state of a lamp switch SW which is operated by a driver or detected signals of an illuminance sensor S which detects brightness of a running environment of the automobile, and controls four relay switches RL11 to RL14 in a relay box, which is disposed in an engine room, based on the lighting control signals. Each of the relay switches RL11 to RL14 is wire-connected so as to perform ON and OFF controls with respect to power lines L11 to L14 connected to the HiL, LoL, CLL, and DRL, and the body ECU 103 controls each of the relay switches RL11 to RL14 and controls the lighting of each lamp. Right lamps (not shown) are similar to the left lamps. However, here, since each of the left and right lamps is simultaneously controlled by one relay switch, four relay switches RL11 to RL14 can be configured. Accordingly, the size of the relay box in which four relay switches RL11 to R14 are built-in is increased, the number of harnesses, which configure control lines Lc connecting each of the relay switches RL11 to RL14 to the body ECU 103 or power lines L11 to L14 for connecting each of the relay switches RL11 to RL14 to each of lamps HiL, LoL, CLL, and DRL, is significantly increased, and thus, there is a problem that a wiring structure is complicated.
With respect to this, in JP-A-2006-62594 discloses that an electric equipment connector is disposed in each of a plurality of lamps and each electric equipment connector performs the lighting control of each lamp based on signals from a control ECU corresponding to the body ECU. In this disclosure, since each electric equipment connector controls the power source with respect to each lamp, the plurality of relay switches shown in FIG. 6 corresponding to the number of the lamps are not needed. However, instead of this, electric equipment connectors in the number corresponding to the number of the lamps are needed, and thus, a configuration of the system is complicated. Moreover, the number of power lines or control lines which connect the control ECU and each lamp is also increased, and thus, it is difficult to decrease the number of harnesses.
Accordingly, in recent years, a system has been suggested, in which one lamp ECU is disposed in a complex type HL and the lighting controls of the HiL, LoL, CLL, and DRL are performed by the lamp ECU. That is, in this system, relay switches are controlled by signals from the body ECU, power supply to the lamp ECU is controlled, and simultaneously, the lamp ECU performs the lighting control of each lamp by lighting control signals from the body ECU. Since only one relay switch is provided for the HL, a reduction in the size is possible, the body ECU and the lamp ECU, that is, the complex type HL may be connected by one power line and one control line, and thus, the number of harnesses is decreased, and the wiring structure can be simplified.
However, this technology can be applied to a lamp in which a plurality of lamps are assembled in one lamp housing as one complex type lamp. However, in a case where the plurality of lamps are configured as an independent lamp, for example, as shown in FIG. 6, in the case where the CLL and DRL are integrated and configured of a lamp (hereinafter, referred to as C/DL) separate from the HL, the lighting control of the separate C/DL cannot be performed by the lamp ECU built in the HL. Accordingly, although one power line can be configured with respect to the HiL and the LoL configuring the HL, with respect to the C/DL, the power lines are needed to be connected to the CLL and the DRL via relay switches respectively, and as a result, a total of three relay switches and three power lines are needed, and it is difficult to decrease the number of harnesses (see e.g., JP-A-2006-62594).
As described above, in the lighting control system of the related art, there is a problem that the number of the relay switches or the number of the harnesses of the power lines, the control lines, and the like is increased in accordance with the number of the lamps. Even in a case where the lamp ECU is provided and the lighting is collectively controlled, in order to solve the problems, there is a problem that reduction effects in the number of the relay switches or reduction effects in the number of harnesses cannot be obtained when some lamps are configured as the separate lamps, and there is a problem that simplification or a reduction of cost of the lighting control system is not easily realized.